As one example of such a rotating mechanism, an electromagnetic rotating machine with a magnet rotor has been proposed (for example, see JP Publication No. 2000-197327).
Here, such rotating mechanism has various bearings which journal the rotary shaft, and the rotating mechanism performance depends on the level of rotation resistance. Hence, it is necessary to minimize the rotation resistance to improve the performance or efficiency as a rotating mechanism.
For this purpose, provision of a mechanism which encourages or assists rotation is considered desirable. However, if rotation of the rotating mechanism is encouraged by supplying an electric current, etc., from outside, the input energy would increase only to lower the efficiency of the rotating mechanism.
In JP Publication No. 2000-197327 referred to above, the object is to obtain a DC motor or DC generator which does not use a commutator, a brush and a position sensor and causes no rib torque nor rib voltage but not to contribute to improvement in rotating mechanism efficiency.